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Jiang P.,Shanghai JiaoTong University | Jiang P.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Sun X.,Shanghai JiaoTong University | Sun X.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | And 6 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2017

Compared with the traditional insulation materials such as cross-linked polyethylene (XLPE), polypropylene (PP) is famous for its better recyclable and thermal properties, as well as good electrical performance. Therefore, selecting PP such as propylene-ethylene copolymer and homo-polypropylene as base resin materials, we studied the influence of adding nano magnesium oxide (MgO) on PP's insulation. First, we prepared a series of nano-composites with 0.5%, 1%, 2%, and 3% MgO contents, and tested the direct current (DC) breakdown strength of samples. According to the main insulation parameters such as DC breakdown strength, the optimum additive content of MgO is 1%. Second, 1% nano-MgO and 5% ethylene-octene elastomer(POE) were added to PP matrix through two different processes to compare the nanocomposites in the presence of pure PP and the blend of PP/POE. Finally, the microstructure, mechanical property and electrical property of all samples were characterized. Results show that nano-MgO, as heterogeneous nucleating agent, can reduce the size of sphaerocrystal and induce the generation of β-crystal in PP. Adding nano-MgO to PP hardly affects the mechanical property. However, it reduces space charge of PP greatly. There was no significant differences in DC breakdown strength and DC superimposed impulse voltage between PP and XLPE. Recyclable thermoplastic PP is a new option for HVDC cable in the future. © 2017, High Voltage Engineering Editorial Department of CEPRI. All right reserved.


Zheng Y.,Shanghai JiaoTong University | Wu J.,Shanghai JiaoTong University | Wang Q.,Shanghai JiaoTong University | Wang Y.,Shanghai JiaoTong University | And 2 more authors.
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012

The nanocomposite is produced by adding different concentrations of nano-MgO, whose particle size is 70 nm, to cross linked polyethylene (XLPE). The high field conduction and space charge distribution of samples are studied with a jointing measuring apparatus of dc conduction and space charge. It is found that the conduction mechanism of XLPE and the composites of nano-MgO/XLPE are not dominant by space charge limited current (SCLC) at the room temperature. At the same time, space charge injection threshold of the samples was calculated. It is shown that the addition of nano-MgO could increase the threshold 30.69% higher than that of pure XLPE. Moreover, it is found that the dc conduction of nano-MgO/XLPE decreases firstly and then increases with the increment of nano-MgO content as dc electrical stress is below the injection threshold. Space charge distribution in all samples is investigated and it is found that nano-MgO could well decrease the hetero-charge accumulation and inhibit electron injection in XLPE.


Wang L.,Shanghai JiaoTong University | Wang L.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Jiang J.,Shanghai JiaoTong University | Jiang J.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | And 4 more authors.
Fire and Materials | Year: 2011

A novel flame retardant (SPDH) containing phosphorus was synthesized through the reaction of 10-(2, 5-dihydroxyphenyl)-9, 10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO-HQ) and synthesized intermediate product 3, 9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro(5.5)undecane-3,9-dioxide (SPDPC). The structure and properties of SPDPC and SPDH were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA). After blending with poly(ethylene-co-vinyl acetate) (EVA), the flame-retardant properties of EVA/SPDH composites were estimated by cone calorimeter, limited oxygen index (LOI) and UL-94 tests, whereas the thermal stabilities were investigated using TGA. The morphological microstructure of the char formed by EVA/SPDH composite after combustion in cone calorimeter was investigated by scanning electron microscopy (SEM). The results indicate that the flame retardant and thermal stability were improved by incorporation of SPDH. The rich foamy char layers were observed from the residues after combustion in a cone calorimeter, which exactly benefits the improvement of thermal stability and flame retardant property of materials. © 2010 John Wiley & Sons, Ltd.


Zhuang Y.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Deng H.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Su Y.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | He L.,Shanghai JiaoTong University | And 4 more authors.
Biomacromolecules | Year: 2016

A novel type of backbone redox-responsive hyperbranched poly(2-((2-(acryloyloxy)ethyl)disulfanyl)ethyl 4-cyano-4-(((propylthio)carbonothioyl)-thio)-pentanoate-co-poly(ethylene glycol) methacrylate) (HPAEG) has been designed and prepared successfully via the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and self-condensing vinyl polymerization (SCVP). Owing to the existence of surface vinyl groups, HPAEG could be efficiently functionalized by DNA aptamer AS1411 via Michael addition reaction to obtain an active tumor targeting drug delivery carrier (HPAEG-AS1411). The amphiphilic HPAEG-AS1411 could form nanoparticles by macromolecular self-assembly strategy. Cell Counting Kit-8 (CCK-8) assay illustrated that HPAEG-AS1411 nanoparticles had low cytotoxicity to normal cell line. Flow cytometry and confocal laser scanning microscopy (CLSM) results demonstrated that HPAEG-AS1411 nanoparticles could be internalized into tumor cells via aptamer-mediated endocytosis. Compared with pure HPAEG nanoparticles, HPAEG-AS1411 nanoparticles displayed enhanced tumor cell uptake. When the HPAEG-AS1411 nanoparticles loaded with anticancer drug doxorubicin (DOX) were internalized into tumor cells, the disulfide bonds in the backbone of HPAEG-AS1411 were cleaved by glutathione (GSH) in the cytoplasm, so that DOX was released rapidly. Therefore, DOX-loaded HPAEG-AS1411 nanoparticles exhibited a high tumor cellular proliferation inhibition rate and low cytotoxicity to normal cells. This aptamer-functionalized and backbone redox-responsive hyperbranched polymer provides a promising platform for targeted drug delivery in cancer therapy. © 2016 American Chemical Society.


Wang L.,Shanghai JiaoTong University | Wang L.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Jiang J.,Shanghai JiaoTong University | Jiang J.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | And 4 more authors.
Journal of Polymer Research | Year: 2010

A novel flame retardant (SPDV) containing phosphorus and silicon elements at the same time was synthesized. Spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) synthesized through simple dehydrochlorination reaction of pentaerythritol (PER) and phosphorus oxychloride (POCl3) was introduced into 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)/ vinylmethyldimethoxy silane (VMDMS) oligomer (DV) to form a novel flame retardant. The structure and properties of SPDPC, DV and SPDV were characterized by FT-IR, NMR and TGA. After blended with EVM, the flame retardance of EVM/SPDV composites was estimated by cone calorimeter, limited oxygen index (LOI) and UL-94, and thermal stability was investigated using TGA. The morphological structure of the char formed after combustion in cone calorimeter was investigated by Scanning Electron Microscopy (SEM). The results indicate that the flame retardant and thermal stability were improved by incorporation of SPDV. The rich foamed char layers were observed in the residues after combustion in cone calorimeter test, which exactly benefits the thermal stability and flame retardant of EVM materials. © 2010 Springer Science+Business Media B.V.


Wang L.,Shanghai JiaoTong University | Wang L.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Jiang P.K.,Shanghai JiaoTong University | Jiang P.K.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging
Journal of Applied Polymer Science | Year: 2011

The synthesized flame retardant 9,10-dihydro-9-oxa-10-phosphaphanthrene-10- oxide/vinyl methyl dimethoxysilane (DV) was used to modify multiwalled carbon nanotubes (MWNTs). The results of FTIR, 1H-NMR, and TGA measurements show that DV has been covalently grafted onto the surfaces of MWNTs, and the MWNTs-g-DV is obtained successfully. Transmission electron microscopy images show that a core-shell nanostructure appears with MWNTs as the core and the DV thin layers as the shell, and the modified MWNTs with DV can achieve better dispersion than unmodified MWNTs in EVM matrix. Thermogravimetric analysis and cone calorimeter tests indicate that the thermal stability and flame retardant are improved for the presence of the MWNTs in EVM matrix. Moreover, the improvement is more evident for EVM/MWNTs-g-DV composite compared to unmodified MWNTs-based composite, which can be attributed to the better dispersion of the DV-modified MWNTs and to the chemical structure of the combustion residue. © 2010 Wiley Periodicals, Inc.


Wang L.,Shanghai JiaoTong University | Wang L.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | Yu J.,Shanghai JiaoTong University | Yu J.,Shanghai Key Laboratory of Electrical Insulation and Thermal Aging | And 4 more authors.
Journal of Materials Science | Year: 2010

A novel flame retardant containing phosphorus-silicon, spirocyclic pentaerythritol bisphosphorate disphosphorylchloride/9,10-dihydro-9-oxa-10- phosphaphanthrene-10-oxide/vinyl methyl dimethoxysilane (SPDV), has been used to modify multiwalled carbon nanotubes (MWNTs) and the m-MWNTs (MWNTs-g-SPDV) was obtained by the covalent grafting of SPDV onto the surfaces of MWNTs. And then the according poly(ethylene-co-vinyl acetate) nanocomposites were prepared via melt blending. Transmission electron microscopy (TEM) results showed that a core-shell nanostructure with MWNTs as the hard core and SPDV as the soft shell was formed, and the resultant m-MWNTs can achieve better dispersion than pristine MWNTs in EVM matrix. Cone calorimeter results showed that better flame retardancy was obtained for EVM/m-MWNTs nanocomposites. Mechanical measurements showed that the Young's modulus increases due to the presence of MWNTs or m-MWNTs. The flammability and mechanical properties of the nanocomposites are strongly dependent on the dispersion state of nanotubes. © 2010 Springer Science+Business Media, LLC.

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